Medical probe devices are utilized for many purposes, chief of which include catheterization, centesis, and biopsy procedures. Percutaneous placement of probes using these devices is often performed with techniques which rely on ascertaining the correct locations of palpable or visible structures. This is neither a simple nor a risk-free procedure. For instance, proper insertion and placement of a subdermal probe depends on correct localization of anatomical landmarks, proper positioning of the patient in relation to the care provider, and awareness of both the depth of the subdermal location and angle from the point of probe insertion. Risks of unsuccessful placement of a probe can range from minor complications, such as patient anxiety and discomfort due to repetition of the procedure following incorrect initial placement, to severe complications, such as pneumothorax, arterial or venous laceration, or delay of delivery of life-saving fluids or medications in an emergency situation.
Ultrasound guided techniques and devices have been developed to aid in correct placement of percutaneous probes. Ultrasound guided techniques often utilize two people, an ultrasound operator who locates the internal site and keeps an image of the site centrally located on a monitor, and a care provider who attempts to guide the probe to the site based upon the sonogram. Such techniques are very difficult perceptually. For instance, these techniques are complicated by the fact that the person guiding the probe to the internal site is not the same person as is operating the ultrasound. In addition, the generally thin, cylindrical probe is usually small and reflects very little of the ultrasound beam. Moreover, as the cylindrical probe and the ultrasound beam are not generally normal to one another, the small amount of ultrasonic energy that is reflected from the probe will reflect at an angle to the incident beam, resulting in little if any of the reflected energy being detected by the ultrasound transducer. As a result, the probe itself is difficult to visualize in the sonogram and the person placing the probe must attempt to guide the probe to the correct location using minimal visual feedback. For example, the only visual feedback available is often only subtle artifacts of the motion of the probe such as slight changes in the sonogram as the probe deflects and penetrates the surrounding tissue. The trained observer can pick up subtle ultrasonic shadow artifacts deep to the probe created when the probe blocks the transmission of the ultrasound beam to the tissue below, and such subtle artifacts can be used to help guide the probe to the desired subdermal location.
In an attempt to relieve the difficulties of ultrasound guided probe techniques, systems have been developed including a probe guide which can be attached to an ultrasound transducer housing. Problems still exist with such devices however. For instance, the probe is often inserted at angle that crosses the scanned plane displayed on the sonogram, restricting the intersection of the scanned plane and the point of the probe to a very small area in space. In addition, even if the probe passes for a length in line with the scanned plane, very little, if any, ultrasonic energy is reflected from the probe back to the transducer. In fact, due to the lack of reflection off of the probe, visual cues to the location of the probe tip may be even more difficult to discern on a sonogram when using these devices. In addition, in many of these devices, the probe passes through the ultrasound beam at a fixed depth range depending on the set angle of the probe guide, and this may not correspond to the depth of the desired subdermal site, in which case it may not be possible to show the juncture of the desired site and the probe tip on the sonogram at all.
What are needed in the art are improved ultrasound devices and methods for using such devices. For instance, what are needed in the art are ultrasound devices that can be utilized by a single operator to accurately visualize the delivery of a probe to a subdermal location.